Steam generating unit



E. F. SPELLMAN STEAM GENERATING UNIT 3 Sheets-Sheet 1 f/O I Filed March 19, 1962 INVENTOR.

EUGENE F. SPELL/JAN I Aug. 18, 196.4 E.YF. SYPELLMAN 7 3,144,855

STEAM GENERATING UNIT Filed March 19, 1962 3 Sheets-Sheet 2 I: I: I! I: I!

26 25 FIG. 3

INVENTOR EUGENE F. SPELLMAN ii mk/wpgw Aug. 18, 1 E. F. SPELLMA-N I ,1 STEAM GENERATING UNIT Filed March 19, 1962 s Sheets-Sheet s FIG. 5

FIG. 6

INVENTOR. EUGENE F. SPELLMAN United States Patent 3,144,855 STEAM GENERATING UNIT Eugene F. Spellman, Shrewsbury, Mass., assignor to Riley Stoker Corporation, Worcester, Mass., a corporation of Massachusetts Filed Mar. 19, 1962, Ser. No. 180,530 4 Claims. (Cl. 122-235) This invention relates to a steam generating unit and more particularly to apparatus arranged to produce steam by the burning of fuel in a combustion chamber.

In the construction of steam generating units, it is common practice to form the furnace in which the burning of fuel takes place in the form of a combustion chamber whose walls are lined with water-filled tubes. In this way, the heat transfer to the water in the boiler may take place by radiation from the burning fuel and hot products of combustion and the walls of the furnace are protected from destruction due to extreme heat. There are many difliculties experienced in the construction of such boiler water-tube lined combustion chambers, notably in the construction of the bottom. It will be readily understood that the bottom of such combustion chambers is subject to extreme reaction to the chemical and heat effects of the combustion which is taking place. This is particularly true in the case where pulverized solid fuel is used and where the incombustible elements of the fuel arrive at the bottom in a molten condition. An opening must be pro vided in the bottom for draining such molten slag from the combustion chamber and, at the same time, there must be no area where the chemically-active molten slag can attack the tubes of the boiler. At the same time, it must be assured that the areas of the bottom are suitably provided with tubes containing rapidly-flowing water and that there are no tubes in which the water is stagnant or moving slowly, so that a very high tube metal temperature is reached. This is particularly true in the area of the slag hole, where destruction of the tubes could most rapidly take place. Prior art bottoms of this type have also been very complicated and expensive. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a steam generating unit having a water-cooled furnace bottom of unusual construction.

Another object of this invention is the provision of a steam generating unit having a combustion chamber bottom made up of water tubes, which bottom is efficient in operation and yet relatively inexpensive to manufacture.

A further object of the present invention is the provision of a slag tap furnace bottom where all portions thereof are provided with water tubes having an adequate flow of water to prevent destruction of the tubes.

It is another object of the instant invention to provide a steam generating unit having a water tube bottom furnished with water from headers underlying the bottom, wherein novel means is provided for supplying the tubes with water and it is not necessary to have such tubes originate in the area of a welded joint of a header.

It is a further object of the invention to provide a steam generating unit having a furnace bottom with an H-shaped header layout, wherein the cross header is provided with an intermediate welded joint and in which, although no tube originates in the vicinity of the welded joint, the bottom is nevertheless provided with an adequate number of tubes.

With these and other objects in view, as will be apparent to those skilled in the art, the invention, resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms as illustrated by the accompanying drawings in which:

FIG. 1 is a vertical sectional view of a steam generating unit embodying the principles of the present invention;

FIG. 2 is a somewhat schematic view of the bottom of the steam generating unit;

FIG. 3 is a vertical sectional view of the invention taken on the line III-III of FIG. 2;

FIG. 4 is a horizontal section of half of the furnace bottom taken on the line IVIV of FIG. 1;

FIG. 5 is another horizontal sectional view of half of the unit taken on the line V-V of FIG. 1; and

FIG. 6 is a transverse vertical sectional view of the unit taken on the line VI-VI of FIG. 2.

Referring first to FIG. 1, wherein are best shown the general features of the invention, the steam generating unit, indicated generally by the reference numeral 10, is shown as consisting of a boiler 11 and a furnace 12 mounted on a supporting structure 13. The furnace is seen as consisting of a front wall 14, a rear wall 15, side walls 16, a roof 17, and a bottom 18 defining a combustion chamber 19.

The boiler consists of a steam-and-water drum 21 from which downcomers 22 terminate in a mud drum 23. The mud drum is connected to the steam-and-water drum by risers 20. The mud drum is, in turn, connected at its ends by two large downcomers 24 to side wall headers 25 underlying the side walls 16. Extending between the side wall headers 25 is a cross header 26. Water-wall tubes extend from all three headers along the bottom roof and walls of the combustion chamber and discharge steam into the steam-and-water drum, in the usual manner. A pulverizer 27 is connected on its inlet to a source of solid fuel (not shown) and its outlet is connected to burners 28 mounted on the side walls 16. The steam generating unit is provided with a superheater 29 and a convection pass 31 through which the gases pass, eventually passing through a rotary regenerative air heater 32 and to the stack.

Referring to FIG. 2, to aid in understanding the construction, the combustion chamber bottom 18 has been divided into six imaginary portions lettered B, C, D, E, F, and G. Extending between the side walls 16 is a dividing line or gap identified by the letters A-A, and in the center on the dividing line and between the portions C and F is a slag tap hole 33. In a general way, the water-wall tubes which cover the portion B (in the corner defined by a side wall 16 and the rear wall 15) originate in the cross header 26. The tubes in the portion C originate in the cross header 26 and so do the tubes which cover the bottom in the portion D (which is the corner between the other side wall 16 and the rear wall 15). The water tubes which cover the floor in the portion E originate in the cross header as do the tubes which cover the bottom in the portion G. The tubes which cover the bottom in the area of the portion F are provided with water tubes, half of which originate in one of the side wall headers 25 and the other half of which originate in the other side wall header 25.

Referring now to FIGS. 3, 4, 5, and 6, which show the details of the bottom 18 and the associated parts of the furnace and boiler, it can be seen that Without exception the tubes which cover the bottom 18 originate either in the side walls 25 or the cross header 26. With particular reference to FIG. 5, it can be seen that a downcomer 24 originating in the center of the mud drum 23 is joined to the center portion of the cross header 26. It is also clear from FIG. 3 that the tubes 30 which cover the portions B, C, and D of the bottom originate in the cross header 26 particularly in the top and rearward parts thereof. Because of the required ligament strength of the metal between the openings into which the tubes are welded, the

Patented Aug. 18, 1964 tubes 30 are taken alternately from the exact top of the drum or from a portion facing slightly rearwardly. These tubes extend upwardly and forwardly and then extend vertically on a curve in the area of the dividing line AA, except in the vicinity of the tap hole 33 where they define the tap hole. These tubes then extend horizontally along the bottom 18 and finally extend upwardly along the rear wall 15 to form the covering for that wall. As is evident in FIG. 3, there is a slight pitch of these tubes along the bottom toward the tap hole 33. Tubes 34 leave the forward-facing parts of the cross header 26 and extend angularly to extend generally vertically along the dividing line AA and then extend generally horizontally to form the portions E and G of the bottom 18, there being a slight pitch toward the tap hole 33. These tubes also form the portions of the front wall 14 adjacent the side walls 16. 'DlbCS 35, originating in the portion of a side wall header 25 adjacent the front wall 14, extend at an upward angle, as is evident in FIG. 6. They are then bent into a horizontal plane spaced well below the bottom 18 at the same time extending forwardly, as is evident in FIG. 5. They are then bent into a vertical curve, shown in FIG. 6, and eventually form the floor of the furnace in one-half of the portion F. The vertical curve forms the lip of the tap hole 33. A similar set of tubes comes from the forward part of the opposite side wall header 25 and forms the other half of the section F of the bottom. These tubes originating in the side wall headers and forming the central portion of the front part of the bottom also extend up the front wall 14 and form the center portion thereof.

In FIG. it can be seen that the cross header 26 is provided with a welded joint 36 and it is noted that there are no tubes 30 or 34 originating in the cross header 26 in the vicinity of the welded joint 36. In order to provide for the bottom tubes which would ordinarily originate in this position, a first tube 37 and a second tube 38 originate in the side wall header 25 and extend outwardly in the vicinity of the joint. The first tube 37 joins the tubes 34 and forms part of the portion E of the bottom, while the second tube 38 joins the tubes 30 and forms part of the portion B of the bottom. Naturally, similar first and second tubes originate in the other side wall header, as is obvious in the drawings, and the first tube 37 and the second tube 38 are shown specifically in every view in which they appear.

The operation of the invention will now be readily understood in view of the above description. The steam generating unit operates in the usual manner with fuel arriving at the burners 28 from the pulverizer 27. The fuel is then mixed with combustion air and firing of the mixture takes place in the combustion chamber 19. The products of combustion pass through the boiler, through the back convection pass 31, and out of the unit through the air heater 32. Water is introduced into the boiler 11 at the steam-and-water drum 21, passes downwardly through the downcomers 22 into the mud drum 23, and then upward through the risers 20. Some of the water passes downwardly through the downcomers 24 into the side wall headers 25 and the cross header 26 underlying the bottom of the furnace. Water is supplied in equal amounts through the three downcomers 24, one of which is in alignment with one side header 25, the other one is in alignment with the other side header 25, and one enters the center of the cross header 26. The number of tubes leaving each header is arranged so that substantially the same amount of flow takes place to each group of tubes. It is particularly noteworthy that those tubes which lie in the center of the furnace (that is to say, in sections C and F) are liberally supplied with water. For instance, the only tubes in the bottom which are supplied from the side header are those in the section F, although, of course, the header must supply the water for the waterwall tubes on the sides 16. The tubes which originate in the cross header 26 and which supply the center section C of the furnace originate in the center part of the cross header close to the connection with the downcomer 24. It should be noted that, because of the provision of the auxiliary tubes 37 and 38, the welded joint 36 in the header 26 has no tube connections close to it. This not only makes for strong construction and for ease in examination of the joint from time to time, but it facilitates the use of sectional field construction in the erection of the boiler.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. A steam generating unit, comprising (a) a furnace having four walls and a bottom defining a combustion chamber, the bottom having a division gap extending between two opposed walls at a position between the other two walls,

(b) a first header underlying each of the said other two walls,

(0) water wall tubes originating in each of the said first headers and extending vertically to define the wall under which the header lies,

(d) a cross header extending between the headers,

(e) water wall tubes extending from the cross header upwardly along the division gap, extending horizontally to define a portion of the bottom between the said division gap and one of the said other two walls, and then extending vertically to define that wall,

(1) water wall tubes extending laterally from the first headers, extending upwardly adjacent the division gap, extending horizontally to define a substantial portion of the bottom, and then extending vertically to define a portion of the other of the said two walls,

(g) and water wall tubes extending from the cross header upwardly adjacent the division gap, extending horizontally to define substantial portions of the bottom, and then extending vertically to define the remainder of the said other of the said other two walls.

2. A steam generating unit as recited in claim 1, wherein the cross header is provided with a welded joint located between its ends, the portion of the cross header adjacent the joint being free of water wall tubes, a first tube originating in a header joining the tubes originating in the cross header, a second tube originating in a header and also joining the tubes, the first and second tubes extending in opposite directions from the division gap and forming the bottom and walls in the vertical plane of the joint.

3. A steam generating unit, comprising (a) a furnace having a front wall, a rear wall, a bottom, and two side walls defining a combustion chamber, the bottom having a central slag tap hole and having a center gap extending between the side walls midway between the front wall and the rear wall,

(b) a side wall header underlying each side wall a substantial distance below the level of the bottom,

(0) water wall tubes originating in each side wall header and extending vertically to define the side wall under which the header lies,

(d) a cross header extending between the side wall headers between the said center gap and the rear wall,

(2) water wall tubes extending from the cross header upwardly along the center gap, extending horizontally to define the portion of the bottom between the said center gap and the rear wall, and then extending vertically to define the rear wall,

(1) water wall tubes extending laterally from the side wall headers, extending upwardly adjacent the center gap, extending horizontally forwardly to define a central portion of the bottom, and then extending vertically to define a central portion of the front wall,

(g) water wall tubes extending from the cross header upwardly adjacent the center gap, extending horizontally forwardly to define lateral portions of the bottom, and then extending vertically to define the portions of the front wall adjacent the side walls.

4. A steam generating unit, comprising (a) a furnace having a front wall, a rear wall, a bottom, and two side walls defining a combustion chamber, the bottom having a division gap extending between the side walls at a position between the front wall and the rear wall,

(b) a side wall header underlying each side wall a substantial distance below the level of the bottom, (0) water wall tubes originating in each side wall header and extending vertically to define the side wall under which the header lies,

(d) a cross header extending between the side wall headers between the said division gap and the rear wall and having a welded joint at one intermediate position, a first tube and a second tube originating in a side wall header,

(e) water wall tubes extending from the cross header and joining the first tube to extend upwardly along the division gap, to extend horizontally to define the portion of the bottom between the said division gap and the rear wall, and then to extend vertically to define the rear wall,

(7) water wall tubes extending laterally from the side wall headers, extending upwardly adjacent the division gap, extending horizontally forwardly to define a central portion of the bottom, and then extending vertically to define a central portion of the front wall,

(g) and water wall tubes extending from the cross header and joining the second tube to extend upwardly adjacent the division gap, to extend horizontally forwardly to define lateral portions of the bottom, and then to extend vertically to define the portion of the front wall adjacent the side walls.

Raynor Sept. 28, 1943 Braddy Aug. 7, 1962 

1. A STEAM GENERATING UNIT, COMPRISING (A) A FURNACE HAVING FOUR WALLS AND A BOTTOM DEFINING A COMBUSTION CHAMBER, THE BOTTOM HAVING A DIVISION GAP EXTENDING BETWEEN TWO OPPOSED WALLS AT A POSITION BETWEEN THE OTHER TWO WALLS, (B) A FIRST HEADER UNDERLYING EACH OF THE SAID OTHER TWO WALLS, (C) WATER WALL TUBES ORIGINATING IN EACH OF THE SAID FIRST HEADERS AND EXTENDING VERTICALLY TO DEFINE THE WALL UNDER WHICH THE HEADER LIES, (D) A CROSS HEADER EXTENDING BETWEEN THE HEADERS, (E) WATER WALL TUBES EXTENDING FROM THE CROSS HEADER UPWARDLY ALONG THE DIVISION GAP, EXTENDING HORIZONTALLY TO DEFINE A PORTION OF THE BOTTOM BETWEEN THE SAID DIVISION GAP AND ONE OF THE SAID OTHER TWO WALLS, AND THEN EXTENDING VERTICALLY TO DEFINE THAT WALL, (F) WATER WALL TUBES EXTENDING LATERALLY FROM THE FIRST HEADERS, EXTENDING UPWARDLY ADJACENT THE DIVISION GAP, EXTENDING HORIZONTALLY TO DEFINE A SUBSTANTIAL PORTION OF THE BOTTOM, AND THEN EXTENDING VERTICALLY TO DEFINE A PORTION OF THE OTHER OF THE SAID TWO WALLS, (G) AND WATER WALL TUBES EXTENDING FROM THE CROSS HEADER UPWARDLY ADJACENT THE DIVISION GAP, EXTENDING HORIZONTALLY TO DEFINE SUBSTANTIAL PORTIONS OF THE BOTTOM, AND THEN EXTENDING VERTICALLY TO DEFINE THE REMAINDER OF THE SAID OTHER OF THE SAID OTHER TWO WALLS. 